Well summed up Lu.......but....... .. .my point was actually that of the two teaching methodologies, the UK one is scientifically substantiated, the US one is not (in regard to the topic). The UK one is long & expensive and offers no real advantage over the simplified and user friendly US approach as it applies to doing the job, other than you will not find a physicist who disagrees with you in the bar!! <img border="0" title="" alt="[Big Grin]" src="biggrin.gif" /> . .. .But we digress. Lu, did you do the experiment? . .. . <img border="0" title="" alt="[Cool]" src="cool.gif" />